Most of the time people ask: What length board is best for me? An often unasked, but equally important question is: What width board is best for you? Both snowboard length and width factor heavily in finding and buying the correct size snowboard.
Length
Length is measured in centimeters and is sometimes abbreviated to just the last two digits. Hence, a Burton Custom 56 is a snowboard made by Burton that measures 156cm from tip to tail. Kids' boards run as short as 100cm and long race or powder boards can be upwards of 180cm.
To find the correct length for you, start by comparing it to your height. When holding the board on its end, a short board will come up somewhere between your collar bones and chin. Because shorter boards are easier to maneuver, they are great to learn on and are preferred by riders who do a lot of trick, park and pipe riding.
A medium length board standing on end will come up between your chin and nose. This length is for the all around intermediate to advanced rider who may ride a variety of terrain, including parks and steeps.
Long boards go from eye-level to several inches over the top of the head. Long boards are for high-speed carving, deep powder and big mountain terrain.
Riders who are heavy for their height can stay within these guidelines, but should look for boards that have a stiffer flex. Lighter riders will need boards with a softer flex. Also, remember that these are general guidelines to get you started; personal preference can also strongly sway your decision of what length board to buy.
Width
While board length has some room for personal preference, board width is directly tied to your foot size. Riders with small feet need narrow boards; likewise, riders with big feet need wide boards.
Board width is measured in either centimeters or millimeters and can be found in the board's specifications under waist width (usually on the tag or in the manufacturer's catalog or Web site). The best way to find the correct board width is to stand on a board that is flat on the ground. Strap or step into your bindings, or place your feet exactly how you would have them when you ride. (This is important because the more angle you ride with, the less your foot will span across the width of the board.)
When standing in riding position, your boots should be flush or slightly over the edges of the snowboard. If your toes and heels don't come close to the edge, you won't be able to apply proper pressure to your edges during a turn. If, on the other hand, your feet hang too far over the edges of the board, your toes may catch in the snow while turning and send you reeling. This phenomenon is sometimes referred to as "toe drag", and it is a drag.